i didn't think of this myself..i've heard of this concept before. but i'm wondering why this idea isn't widely used. take a loud lawnmower, for example. why can't you put a device on it that detects the sound it is making (microphone) and then produces sound waves that cancel out the detected sound? could we not basically have silent lawnmowers?
here's some more good ones: http://www.howstuffworks.com/question281.htm http://www.howstuffworks.com/question456.htm http://www.howstuffworks.com/question245.htm
you could, but the computing power and equipment are still too large and expensive to be practical for something like a lawnmower. there has been progress with this idea for larger applications, like aircraft engines and heavy industry (possibly in the auto field?). but in 10 yrs, who knows...?
They've had noise-cancelling headphone for years that do just that. In a controlled environment like an earcup it's a lot eaiser than outside where the lawnmower's sounds would echo off other objects. The acoustic logarithm would be a nightmare.